Monoazo dye and process of making same.



UNITED STATES PATENT OFFICE.

WVERKE, VORM.

MEISTER, LUOIUS & BRIINING, OF HOOHST-ON-THE-MAIN,

GERMANY, A CORPORATION OF GERMANY.

MONOAZO DYE AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 714,882,, dated December 2, 1902.

Application filed September 4,1901.

To all whom it nuty concern.-

Be it known that I, OTTO ERNST, Ph. D., a citizen of the Empire of Germany, residing at Hochst-on-the-Main, Germany, have invented certain new and useful Improvements in the Manufacture of Red Monoazo Dyestufis Suitable for the Preparation of Lakes, of which the following is a specification.

This invention relates to the manufacture ofa dyestuff by combining diazotized paranitranilin-ortho-sulfonic acid with beta-naphthol. I have found that the azo dyestuifwhich may be thus obtained is highly suitable for the preparation of insoluble color-lakes fast to water, acid, lime, and light, being distinguished by these valuable properties, especially that of fastness to light, from the ponceaux of corresponding shade used in the manufacture of lakes. The dyestuff similar in shade obtained from para-nitranilin-ortho sulfonic acid has also various advantages when compared with the dyestufi obtained from diazotized para -nitranilin and betanaphthol. First of all, the dyestuff has not the property of dissolving in oil, which permits of a more extended application than is the case with the dyestnlf obtained from paranitranilin. Further, the new dyestuff may be obtained as such, being afterward transformed into lakes, whereas the dyestuff from para-nitranilin must be produced directly as a lake, which is very inconvenient in the manufacture of lakes, because by this process it is more difficult to obtain uniform re- 3 5 sults than is the case with finished dyestuffs. The manufacture of the new dyestulf is illustrated as follows: 1.2 kilos of ammonium nitranilin-ortho-sulfonate are diazotized in a dilute solution of hydrochloric acid by ni- Serial N0- 74 8l7. (N0 specimens.)

trite, avoiding a considerable excess of hydrochloric acid. The diazo compound is then slowly run into a solution of 0.75 kilos of beta-naphthol in the equivalent quantity of soda-lye and 0.35 kilos of sodium carbonate.

The dyestuff obtained from para-nitranilinortho-sulfonic acid forms a red precipitate of metallic luster. It is very slightly soluble and may be completely separated by adding a little common salt. The dyestuif being soluble with difficulty in water it is best to employ it as paste. With alkaline earths and metallic salts the dyestuif forms intenselycolored lakes of a pure-red shade and of remarkable fastness to light, especially the said color-lakes are far superior to those obtained from known azo dyestuffs ofa similar shade.

Having now described my invention, what I claim is- 1. The herein-described process of making a red monoazo dyestuif for the preparation of color-lakes, which consists in combining the diazo compound of para-nitranilin-orthosulfonic acid with beta'naphthol, substantially as set forth.

2. As a new product, the red monoazo dyestuff obtainedas herein described, being when dry a brick-red powder soluble with difficulty in water and forming according to the usual methods color-lakes of red shades of remarkable fastness, especially to light, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed my name in pres ence of two subscribing witnesses.

OTTO ERNST.

Witnesses:

ALFRED BRIsBoIs, HEINRICH HAHN. 

